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The paper studies the characteristics of eddy current (EC) distribution in carbon fiber reinforced polymer (CFRP) laminates so as to guide the research and operation of eddy current testing of CFRP. To this end, an electromagnetic field computation model of EC response to CFRP based on the finite element method is developed. Quantitative analysis of EC distribution in plies of unidirectional CFRP reveals that EC changes slowly along the fiber direction due to the strong electrical anisotropy of the material. Variation of EC in plies of multidirectional CFRP is fast in both directions. The attenuation of EC in the normal direction in unidirectional CFRP is faster than that in isotropic material due to faster diffusion of EC. In multidirectional CFRP, EC increases near the interfaces of plies having different fiber orientations. The simulation results are beneficial to optimizing sensor design and testing parameters, as well as damage detection and evaluation.

For epigeal seeds, cotyledons experience soil resistance as they move up through soil during the emergence process. Understanding cotyledon-soil dynamics is important for seedbed preparation to promote good seedling emergence. A discrete element model (DEM) was developed to simulate soybean seedling emergence. The cotyledon of soybean was represented by an ellipsoid according to the measured shape. Soil particles were represented by an assembly of spherical particles. As the cotyledon moved upwards through the soil particles, the cotyledon-soil dynamic characteristics were monitored for different cotyledon sizes and orientations (from lying flat to standing vertically). The cotyledon-soil dynamic characteristics (soil resistance, number of soil-cotyledon contacts, and soil kinetic energy) significantly increased as the cotyledon size increased, and generally decreased as the cotyledon angle increased. The simulated soil resistance to cotyledon was 7.08 N that was comparable with the experimental value of 8.02 N reported in the literature. The soil resistance increased from 1.64 to 15.4 N as the cotyledon size increased from 4 to 14 mm, which indicated that smaller seeds would have advantages in terms of soil resistance. A more vertically inclined cotyledon had less resistance force from the soil, which partially explained why hypocotyl tends to pull or push the cotyledon to a relatively upright position during the emergence of a seedling. The proposed model was able to provide useful insights into the micro-mechanics of the seedling emergence through soil.

Conventional seismic-based techniques for analysis of the progradational stages usually proceed qualitatively according to the facies identified by 2D seismic or cross-well sections. In this study, we try to apply a more quantitative and practical approach to depict the distribution and stacking patterns of the progradational clinoform set (PCS) based on the integrated analysis of well-tie seismic stratigraphy, seismic sedimentology and seismic geomorphology. The Baiyun Sag, a subbasin of the Pearl River Mouth Basin in the South China Sea, provides a suitable example for characterising the clinoform sets with typical progradational seismic reflections. The characterisation results indicate that there were three PCSs and at least nine stages of clinoform that developed during the deposition of the upper member of the Enping Formation (Lower Oligocene). The spatial-temporal distribution of the PCSs can be easily detected by the energy half-time seismic attribute based on the manual interpretation of top and bottom interfaces of each clinoform. Integrated with the progradational seismic facies, progradational angles-based rose diagrams, and seismic geomorphology analysis, the characteristics of each PCS are depicted with stable and gradually increasing sediment supply along the NW-SE direction (azimuths of 130°–160°). The three PCSs display obviously continuous prograding towards the basin centre, whereas several clinoforms (PCS-1-a and PCS-1-b; PCS-3-a and PCS-3-b) exhibit a retrogradational characteristic within one PCS. The overall progressive characteristics, which include having some short period regressive stacking patterns, exhibit a combined effect of sea level change of the South China Sea and the increasing sediment supply intensity from the South China Block.

In this paper, a method of detecting fiber waviness in carbon fiber reinforced polymer (CFRP) using eddy current (EC) probe is proposed. The probe consists of a rectangular excitation coil and a rectangular reception coil that are perpendicular to each other. The excitation coil is along the designed fiber direction. Fiber waviness changes the direction of EC and generates a magnetic field component that is normal to the reception coil; thereby an output signal is obtained. The results of simulation and experiments show that the resolution of testing fiber direction using the proposed method is as small as 0.5° and fiber waviness can be detected according to the variation of scanning signal.

This paper comparatively investigated the removal efficiency and mechanisms of rice straw biochars prepared under three pyrolytic temperatures for two kinds of tetracycline and quinolone antibiotics (doxycycline and ciprofloxacin). The influencing factors of antibiotic adsorption (including biochar dosage, pH, background electrolytes, humic acid, initial antibiotics concentration, contact time, and temperature) were comprehensively studied. The results suggest that biochars produced at high-temperature [i.e., 700°C (BC700)], have higher adsorption capacity for the two antibiotics than low-temperature (i.e., 300–500°C) biochars (BC300 and BC500). Higher surface area gives rise to greater volume of micropores and mesopores, and higher graphitic surfaces of the BC700 contributed to its higher functionality. The maximum adsorption capacity was found to be in the following order: DOX > CIP. The π-π EDA interaction and hydrogen bonding might be the predominant adsorption mechanisms. Findings in this study highlight the important roles of high-temperature biochars in controlling the contamination of tetracycline and quinolone antibiotics in the environment.

This paper develops successfully SVPWM voltage vector tracking current control model for three-phase grid-connected inverter and a novel current scheme under two phase synchronous rotating frame is presented, which is using grid feed forward controller. Considering the efficiency of photovoltaic modules, using an improved maximum power tracking algorithm. The simulation results show that the inverter has high output power factor and photovoltaic system has good dynamic performance and tracking result.

Effective diagnosis of mild cognitive impairment (MCI), in many cases preceding dementia, is important in determining the efficacy of dementia treatments. Inherent in the transition from normal ageing to MCI to and then to dementia is cognitive decline, which can be detected using multiple assessments over an extended period of time. Computerized cognitive tests arise as a promising way of long-term cognitive monitoring in home environment and supplementing clinical evaluation. Compared to conventional paper-and-pencil tests, they are cheaper, more repeatable, and easier to distribute and administer. Over the years, research efforts have been devoted to improve the validity, reliability and comprehensiveness of the computerized cognitive tests. However, it has long been omitted that the usability and entertainment aspects are also crucial to their overall effectiveness and user experience. To reduce drop-out rates and improve effectiveness of long-term cognitive monitoring, we present a first-of-its-kind gamified computerized cognitive test battery, called Virtual ADL+ House. It consists of a series of mini-games, each embedded a cognitive test and featured one of the daily living activities in the Lawton IADL. Virtual ADL+ House can be used to monitor cognitive functions in long-term, alert signs of cognitive decline and provide longitudinal data to facilitate clinical diagnosis. In focus group studies conducted with doctors and older adults, we received positive feedback on the usability and entertainment value of Virtual ADL+ House. We plan to evaluate the validity and reliability of it in subsequent studies. NRF (Natl Research Foundation, S’pore) MOH (Min. of Health, S’pore) Accepted version

The process of arguing is also the process of justifying and explaining. Transparent reasoning process endows argumentation good explainability. Recently, more research efforts have been devoted to realizing the explanatory power of argumentation in unipolar argumentation frameworks. In addition to the attack relation, bipolar frameworks consider the support relation, which brings greater expressibility but also complexity. It is worth exploring how the interactions encompassed in the support relation contribute to the arguing process and how to capture them in explanations. In this paper, we propose a “stronger” notion of defence and a new bipolar admissibility semantics, which are defined based on both the attack and the support relations, and use them to formalize two types of explanations, namely concise and strong explanations. We then present complete and sound processes for computing explanations by constructing bipolar dispute trees. NRF (Natl Research Foundation, S’pore) MOH (Min. of Health, S’pore) Accepted version

A typical eddy-current testing (ECT) process involves scanning of conducting test sample using an EC probe, which can be an air-core coil or ferrite-core coil. Its accurate and efficient modeling is critical to probe and testing parameter optimization. The finite-element method (FEM) has been widely used in ECT simulation. Unfortunately, the conventional FEM is cumbersome and inefficient when the movement of a ferrite-core coil is to be considered, because the change of the coil position results in repetition of meshing as well as generating and preconditioning matrix equation. In this paper, we resolve the problem by dividing the solution domain into subdomains. The test sample and the ferrite core are assigned to different subdomains, and each subdomain is meshed independently. The excitation coil is not included in a subdomain, and its contributions to the magnetic fields in both subdomains are calculated analytically. Solutions of the subdomains are coupled by calculating the contribution of the induced current or magnetization current in a subdomain to the magnetic field in the other subdomain. The proposed method has the merits of easy mesh generation and efficient and accurate solution.

Biochar is regarded as a promising new class of materials due to its multifunctional character and the possibility of effectively coupling different properties. With increasing introduction into the environment, environmental chemicals such as surfactants will load onto the released biochar and change its physicochemical characteristics and adsorption behavior toward pollutants. In this study, sodium dodecyl sulfate (SDS), as one type of anionic surfactant, was coated onto biochar with different loading amounts. The influence of SDS loading onto biochar's physicochemical properties were investigated by Fourier transform infrared (FT-IR) spectroscopy, elemental analysis, zeta potential and Brunauer-Emmett-Teller (BET) surface area and pore size distribution analysis. Results showed that the pore size of the biochar decreased gradually with the increase of SDS loading because of the surface-adsorption and pore-blocking processes; the pH of the point of zero charge (pHPZC) decreased with increasing SDS loading. Although surface-coating with SDS decreased the pore size of the biochar, its adsorption capacity toward Methylene Blue (MB) significantly increased. The biochar-bound SDS introduced functional groups and negative charges to the biochar surface, which could thus enhance the adsorption of MB via hydrogen bonding and electrostatic interaction. The results can shed light on the underlying mechanism of the influence of anionic surfactants on the adsorption of MB by biochar.

The effects of potassium (K) salts loading on CaO on the H 2 production from pyrolysis-gasification of wheat straw were investigated. The loading of 0.25 wt% KCl could significantly enhance the CO 2 absorption capability of CaO. The CO 2 concentration in the product gas decreased sharply from 20.83 to 11.70 vol%, and the H 2 concentration increased from 48.2 to 55.5 vol%. While the loading of 0.25 wt% K 2 CO 3 /K 2 SO 4 inhibited the enhancing effect of CaO. Further increasing the loading of KCl on CaO, the CO 2 absorption of CaO declined, but the catalytic effect of KCl on the gasification process was promoted. The loading of 0.25 wt% KCl on CaO significantly improved the cyclic performance of CaO during the pyrolysis-gasification process. Higher H 2 concentration and more CO 2 absorbed by CaO were obtained with the loading of 0.25 wt% KCl even after 5 cycles compared with those of pure CaO in the first cycle.

In the present paper a band pass microwave filter with spoof surface plasmon polaritions (SPPs) structure is designed and simulated using FDTD method. The filter is composed of four sections, where in the third section, parallel and symmetrically arranged corrugated metallic strip is the spoof SPPs transmission line, in which, periodically arranged rectangular slot is designed to fulfill the spoof SPPs effect. In the fourth section, the spoof SPPs lines are coupled with each other to realize the transmission zero in the up stop band range. The transmission and reflection properties of the spoof SPPs filter in microwave frequency region are elaborately investigated by FDTD method. Through adjusting the geometrical dimensions of the plasmonic coupling structure as well as the rectangular slots structure, the bandwidth and suppression characteristics of the filter can be precisely controlled and the filter has great resistant ability to space electromagnetic interference.

A new type spoof surface plasma polaritons (SSPPs) band pass filter was devised successfully. The filter possessed three-section structure of composite groove, the co-planar wave guide as the first section, microstrip wave guide as the second section, and SSPPs as the third section. It should be noted that there is a interdigital structure or composite composite groove structure in the first or third section, which are carried out by the simulation on characteristics of upper drag band and bandwidth for band pass filter. These results indicated that the filter had bandwidth between 3.1504GHz and 6.3398GHz during −3dB–0dB, the ripple jitter in the passband being better than 0.8dB, and reflection being less than −10dB. This new type of SSPPs filter will be certain engineering value in the application of microstrip circuit, microwave base station and radar microwave communication system between L band and X band.

Pulsed eddy current (PEC) testing has attracted researchers' interest because the pulsed excitation comprises a broad band of frequencies and the response signal provides more information about defect than traditional eddy current testing. Various features have been extracted from PEC signal for defect characterization. In this paper, we extract frequency-domain features and propose defect characterization scheme for identifying defect's location, radius, and height.

Few studies have focused their attentions on the source-to-sink (S2S) system from a multiple-level perspective. We have proposed an effective multilevel S2S subdivision approach based on the integrated study of seismic geomorphology, well-based facies, seismic facies and multi-attribute. The inspiration of multilevel S2S subdivision method is drawn mainly from the modern Diancang Mountain- Lake Erhai S2S system with different-orders of drainage divides. The Paleogene Central Uplift system during the syn-rift stage in Xijiang Sag, Pearl River Mouth Basin, South China Sea, provides a suitable example to test the approach and analyze the multilevel S2S characteristics of an ancient uplift system. The result shows that the Central Uplift system can be divided into three second-level sub-S2S systems (R-A, R-B and R-C), and can be further sub-divided into twelve third-level sub-S2S systems (A1∼A5, B1∼B5 and C1∼C2). Generally, the A1∼A5 and B1∼B4 systems are developed at the gentle slopes and deposited a series of narrow-shaped braided deltas with higher exploration potential, whereas the B5 and C1∼C2 systems are developed at the relatively steep slopes and deposited a series of lobate shaped turbidite and fan deltas with lower reservoir quality. Based on the multilevel S2S analysis, the ancient uplift can be scientifically sub-divided and compared with each sub-S2S system, including the sediment-transport type and distance, sedimentary facies characteristics and stacking relationship with the hydrocarbon source rocks. These in-depth and detailed studies have practical significance for the exploration of favorable reservoir sandbodies and stratigraphic-lithologic traps.

Prediction and optimization of energy consumption is valuable to recognize the status and assist in green campus retrofitting and energy efficiency making. The study focused retrofit strategies in subtropical Guangzhou to achieve energy efficiency in a higher educational campus. According to the building's envelope features, optimization using a pseudo orthogonal test based on assumption of window design. In this paper, field investigation and numerical simulation were used to assess the thermal performance of this building. The prediction was primarily verified using a numerical simulation with 16 cases. It was concluded: (1) on basic cases, the results revealed the methods' reliability based on Energy-plus is adopted in the green campus; (2) the retrofit cases in thermal performance considering the building envelop, solar shading and windows' glazing; (3) the rooms of divergent orientation play varied significant role in energy consumption. The study provided the technic support for the energy optimization strategies of campus building in hot humid area.

The genome sequence of a simian adenovirus from a cynomolgus macaque, denoted CynAdV-1, is presented here. Phylogenetic analysis supports CynAdV-1 in an independent clade, comprising a new simian adenovirus (SAdV) species. These genome data are critical for understanding the evolution and relationships of primate adenoviruses, including zoonosis and emergent human pathogens.

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The inherent alkaline metals in biomass material are known to be volatile during biomass pyrolysis. However, there are very limited works about the investigation of the influence of alkaline metal on hydrogen production from downstream catalytic reforming of pyrolysis vapors. In this study, the influence of volatile K inside the cellulose sample was investigated in terms of hydrogen production and catalyst stability using a two-stage fixed-bed reaction system in the presence of a Ni/Al 2 O 3 catalyst. When the content of K in the cellulose sample was increased from 0 to 15%, the deposition of K on the surface of the reacted catalyst was kept constant at around 0.5 wt.% in terms of the weight of the catalyst. The life time test shows that hydrogen production was around 28 (mmol g −1 cellulose) for each experiment, when the catalyst was reused 5 times using the pure cellulose sample. However, the hydrogen production was significantly reduced to 22 (mmol g −1 cellulose) after the catalyst was reused 5 times with the 2.5% K/cellulose sample. X-Ray Fluorescence analysis shows that the reduce hydrogen production might be ascribed to the increase of the K deposition on the surface of the reused catalyst.

Prospective memory (PM) failure, which is the failure to recall future events or intentions, can lead to serious consequences. Although many PM aid systems have been developed, there are three critical challenges which are yet to be addressed by any existing systems: (1) determining appropriate number of reminders, (2) arranging effective reminder schedule and (3) selecting appropriate reminding method based on context. We propose a new reminding model to address these three challenges. The model draws its theoretical basis from existing PM research and employs Fuzzy Cognitive Maps to incorporate the theoretical basis computationally. Specifically, poring over extensive PM literature, a number of factors and contextual elements are identified, which can help determining the number of reminders and selecting appropriate reminding method. The proposed model captures the complex and dynamic relationships among the factors and elements computationally. To evaluate the proposed reminding model, it was incorporated into a mobile app, ReminderPM. A field study was carried out to evaluate it. Study results support that ReminderPM can provide a better overall experience and remind more effectively.

A microwave miniaturized bandpass filter using (Mg 0.95 Ca 0.05 )TiO 3 (abbreviated as 95MCT hereafter) ceramic substrate is investigated in the present paper. The paper studies the sintering and microwave dielectric properties of Al 2 O 3 , La 2 O 3 and SiO 2 co-doped 95MCT. The XRD pattern shows that a secondary phase MgTi 2 O 5 is easily segregated in 95MCT ceramic, however, through co-doping it can be effectively suppressed, and the microwave dielectric properties, especially, the Qf value can be significantly improved. Through optimizing the co-doping ratio of Al 2 O 3 , La 2 O 3 and SiO 2 , the sintering temperature of 95MCT ceramic can be lowered by 80°C, and the microwave dielectric properties can reach Qf=61856GHz and e r =19.84, which indicates the modified 95MCT ceramic have a great potential application in microwave communication devices. Based on this, we also designed a miniaturized microwave bandpass filter (BPF) on modified 95MCT substrate. Through a full wave electromagnetic structure simulation, the results show that the center frequency of the BPF is 2.45GHz and the relative bandwidth is 4.09% with the insertion loss of less than 0.2dB in the whole bandpass.

To alleviate the rapidly increasing need of the healthcare workforce to serve the enormous ageing population, leveraging intelligent and autonomous caring agents is one promising way. Working towards the design and development of dedicated personal silver assistants for older adults, we follow the human-centred design approach. Specifically, we identify a number of human factors that affect the user experience of the older adults and develop an agent named Mobile Intelligent Silver Assistant (MISA) by applying these human factors. Integrating multiple reusable services onto one platform, MISA acts as a single point of contact while simultaneously providing easy and convenient access to a wide range of personalized services to support a more independent and active lifestyle of the older adults. Furthermore, the architecture of MISA would allow new services to be incorporated easily in the future. NRF (Natl Research Foundation, S’pore) Accepted version

European Commission (SYMPOSIUM Project) [285549]; European Commission (FP7 Theme) [FoF-ICT-2011.7.4]; Association EURATOM/ENEA/CREATE

This paper presents a new finite element (FE) model for three-dimensional simulation of eddy current testing of aircraft skin structure. More specifically, scanning of ferrite-core probe over aluminum plates riveted by steel fasteners is simulated. The model uses different FE meshes to discretize the ferrite core, the aluminum plates, and the fasteners. The coil is not meshed. The reduced magnetic vector potential generated by the induced currents and/or magnetization in each domain is calculated and updated by an iterative procedure. Re-meshing due to changing probe position in conventional models is avoided. Efficiency of the model is demonstrated.

Eddy-current testing (ECT) is widely used in inspection of multilayer aircraft skin structures for the detection of cracks under fasteners (CUF). Detection of deep hidden CUF poses a major challenge in traditional ECT techniques largely because the weak eddy-current signal due to a subsurface crack is dominated by the strong signal from the aluminum or steel fastener. Giant magnetoresistive (GMR) sensors are finding increasing applications in directly measuring weak magnetic fields associated with induced eddy currents. The measured flux image at a fastener site is in general symmetric and an asymmetry is introduced by the presence of a subsurface crack, which is used for defect detection. This paper presents novel methods that employ the resident phase information, for improving detection probability of GMR signal analysis. Using computational model, the effectiveness of the proposed methods for enhancing detection of CUF is investigated. Results demonstrating the potential of these techniques for detection of second layer CUF are presented.

A novel design of eddy current probe based on rotating magnetic fields is presented for the inspection of steam generator tubes in nuclear power plants. A major advantage of the rotating field probe is that it offers the same functiona lity as that of a rotating probe coil without the need for mechanical rotation, which in turn translates into higher operating sp eed. The probe design is also sensitive to cracks of all orientations in the tube wall.

Industrial components are often case hardened to improve their strength and wear characteristics. Traditionally, component samples are collected from the production line at specific intervals and destructively tested for case depth profile assessment. This process is time-consuming, laborious, and can potentially allow an improperly treated component to escape detection. This paper presents a novel nonlinear eddy current technique for assessing the case hardening profile based on the premise that the magnetic characteristic of the case hardened region is different from that of the host material. A custom electromagnetic excitation-sensor array is used to both apply sinusoidal excitations to the component and measure the nonlinear response at multiple excitation frequencies and spatial locations, taking advantage of the different penetration regions due to the skin depth phenomenon. Each response signal obtained from the component under test is compared with that from a reference component subjected to the same excitation. Two pattern recognition algorithms (an artificial neural network and the Iterative Dichotomiser 3 (ID3) algorithm) are then used to process selected characteristics of the difference signal to determine the case depth profile of the component. The nonlinear eddy current technique has been applied to evaluate the case hardening profile of automotive bearing assemblies. This problem is challenging due to the variations in geometry across assemblies as well as the limited accessibility to the case hardened surface. In the neural network test, the system achieved a 95.77% accuracy. For the ID3 algorithm, the system achieved a 95.65% accuracy. These results demonstrate that the nonlinear eddy current inspection technique is highly promising in characterizing the case profile of induction hardened parts.

Research in nondestructive evaluation is constantly increasing the sensitivity of detection of small cracks embedded deep in layered aircraft structures. Pulsed eddy-current (PEC) techniques using coil probes have shown considerable promise in detection and characterization of buried cracks in multilayered structures. In this paper, we describe the design and development of a nondestructive inspection system that uses pulse excitation of a planar multiline coil to generate a transient field that is detected via a giant magnetoresistive (GMR) field sensor. An analysis algorithm using features in time and frequency domain processes the experimentally measured signals for automatic detection of small cracks under fasteners in multilayered structures at a depth of up to 10 mm.

The finite-element method is widely used in modeling eddy-current phenomena. However, its application in eddy-current nondestructive testing involving probe motion requires remeshing for each coil position. Remeshing is not only cumbersome but also a major source of computational noise. We have used the reduced magnetic vector potential formulation to model an air-core probe scan without remeshing the coil in different positions. In this paper, we present a method to model the scanning of ferrite-core probe. With this method, finite-element meshes for the test sample and the ferrite core are generated separately. The coil is not meshed. The magnetic field and magnetic vector potential due to the coil are evaluated analytically. An iterative but fast procedure is used to update the total field. The method is simple, flexible, accurate, and efficient.

Background Although advanced multiple imputation (MI) methodology has become widely introduced and increasingly used, few have reported for health surveillance, where missing incoming data is a common and serious problem. This study examined the application of MI for incomplete income data in population-based health surveillance. Methods In the 2002-2003 Los Angeles County Health Survey (N = 8 167), self-reported household income converted into Federal Poverty Levels (FPLs) was imputed using MI for 1 381 (16.9%) missing cases. Validity was assessed with the 6 786 completed cases where 1 381 FPLs were randomly masked and MI was applied. Consistency was examined by Z tests comparing imputed and original FPL statistics. Multiple imputation statistical inference was examined by estimating 95 percent confidence intervals of Pearson correlation coefficients with 5 percent, 10 percent, 15 percent, and 20 percent of masked and imputed FPL and with different sets of covariates and comparing them with original correlation coefficients. Results Among 188 major surveillance statistics, Z tests showed that imputed and original FPL were consistent by 96.3 percent as demographics but only 19.4 percent as outcome variables. With well-established covariates, powerful MI statistical inference was indicated when missing proportion was within 15 percent, but it started fading out as the missing proportion increased to 15 percent and over. Conclusions Multiple imputation provides a feasible approach and produces differing results for incomplete income data in population-based health surveillance. It performs better for demographic variables than for outcome variables and is more powerful with lower missing proportions than higher ones. With well-established covariates, MI statistical inference could be reliable for missing proportions up to 15 percent.

Three-dimensional finite element (FE) modeling of remote field eddy current (RFEC) technique has been performed to detect localized defects in ferromagnetic steam generator tubes. The excitation frequency, intercoil spacing, and the design of localized receiver coil have been optimized using this model. Amplitude and phase of RFEC signals of radial and axial receiver coils have been predicted for a through hole and two flat bottom holes (FBH). The detection sensitivity of the receiver coils has been compared, and the model has been validated for a few cases.

The use of reduced magnetic vector potential (RMVP) in the three-dimensional finite element analysis of eddy current nondestructive testing (ECT) has demonstrated great flexibility, accuracy, and efficiency in case of coil excitation. This paper investigates the application of the RMVP in another class of eddy-current testing applications where the test sample of finite size is immersed in a uniform excitation field. The paper also shows that RMVP cannot be used in eddy-current testing problems having infinite current foil and infinite conducting plates.

This paper presents a signal inversion technique in nondestructive evaluation (NDE) application for defect profile reconstruction using the element-free Galerkin (EFG) method and state space search. The advantage of EFG method is that it relies only on a set of nodes, instead of a complex mesh to discretize the solution domain. In the inversion procedure, remeshing is avoided to increase the efficiency and accuracy of the solution, which is a major advantage over the traditional finite-element method (FEM). The iterative state space search method using the tree structure is developed for implementing the defect updating scheme. Preliminary results are presented for validation. The robustness of the technique has been shown on noisy signals.

Magneto-optic imaging (MOI) is an emerging hybrid imaging technique that innovatively generates two-dimensional images by combining electromagnetic and optical energies. It has been widely used in detecting surface and subsurface cracks and corrosion in aircraft skins for nondestructive testing purpose. The merits of the MOI that make it attractive include rapid and large-area inspection, insensitivity to liftoff variation, and easy interpretation in contrast to the complex impedance data of conventional eddy current inspections. The early instrument provides binary images of the anomalies based on eddy current induction techniques and an MO sensor using the Faraday’s rotation effect. This chapter will give a comprehensive review on this relatively new sensing technology and discuss the recent advances on MOI including the development of novel optical sources and magnetic film materials for various applications, the integration of MOI sensors with automated systems, and the state-of-the-art post-processing algorithms.

According to the present situation and trend of industrialization of electronic waste at home and abroad, combining the reality of Liupanshui region of electronic waste recycling. This paper studies on the technology and process of electronic waste recycling being basic on the precious metals which recover from the electronic circuit board. Using water elutriation to Prepare blister copper process is simple and the key technology is the waste water solid-liquid separation technology which combines with the research on the hydrometallurgy of chemical method and physical method research. In order to realize the real recycling, zero pollution, zero emission and to receive precious metals which matches with the national standards. As well as to lay a solid foundation for creating Liupanshui circular economy demonstration city and national environmental protection model city.

Building three-phased inverter mathematics model of voltage vector tracking current controller based on Space Vector Pulse Width Modulation (SVPWM) and a novel current scheme under two phase synchronous rotating frame is presented, which uses grid feed forward controller. At the same time, considering the efficiency of photovoltaic modules, using an improved maximum power tracking algorithm. The simulation results show that the off-grid inverter output current stability, Waveform distortion smaller; and photovoltaic system has good dynamic performance and tracking results. When the load changing, the system can always maintain a constant output voltage.

Magneto-optic/eddy current imaging (MOI) has become increasingly popular for inspecting aging aluminum airframes for cracks and corrosion due to its accuracy, reliability, and ease of use. As inspection requirements change, modifications to the MOI system must be made to improve sensitivity and resolution to reliably detect smaller and/or deeper defects in the aircraft structure. Incorporating such improvements by "cut and try" methods is time-consuming and expensive. Therefore, a numerical simulation model that produces quantitative values of the magnetic fields associated with induced eddy currents interacting with structural defects is an essential complement to the instrument development process. Such a model provides a convenient tool for parametrically evaluating the effectiveness of the MOI for detecting various structural defects. This paper presents a three-dimensional finite-element model of Maxwell's equations, utilizing the A-V formulation for numerical simulation of the MOI operation. The model is used to predict quantitative values of field distributions that produce the binary magneto-optic images of subsurface fatigue cracks at rivet sites in an aluminum airframe structure. A parametric study is performed to determine the effects of MOI operational parameters on the binary images. A skewness parameter based on the binary images is established to provide a measure of defect size. This parameter will prove useful for automatic detection and classification of defects. The model-generated images show good agreement with experimentally derived MOI images

The capability of a natural gas transmission pipeline inspection tool to detect cracks and corrosion is affected by a number of factors, namely, magnetization level, sensor spacing, radial liftoff, and circumferential alignment of the sensors relative to a defect. The first two factors are design parameters and are controllable factors. The last two factors are hard to control on site and are treated as noise factors. The Taguchi method is utilized to obtain an efficient set of design parameters that are robust with respect to noise and other variations in test parameters. This article first introduces the basic idea underlying the Taguchi method. Procedures for designing and simulation of experiments are given along with simulation results, which are analyzed using the main effects and analysis of variance techniques. Conclusive remarks based on the analysis are finally summarized.

Human adenoviruses (HAdVs) are highly contagious pathogens causing acute respiratory disease (ARD), among other illnesses. Of the ARD genotypes, HAdV-7 presents with more severe morbidity and higher mortality than the others. We report the isolation and identification of a genome type HAdV-7d (DG01_2011) from a recent outbreak in Southern China. Genome sequencing, phylogenetic analysis, and restriction endonuclease analysis (REA) comparisons with past pathogens indicate HAdV-7d has re-emerged in Southern China after an absence of twenty-one years. Recombination analysis reveals this genome differs from the 1950s-era prototype and vaccine strains by a lateral gene transfer, substituting the coding region for the L1 52/55 kDa DNA packaging protein from HAdV-16. DG01_2011 descends from both a strain circulating in Southwestern China (2010) and a strain from Shaanxi causing a fatality and outbreak (Northwestern China; 2009). Due to the higher morbidity and mortality rates associated with HAdV-7, the surveillance, identification, and characterization of these strains in population-dense China by REA and/or whole genome sequencing are strongly indicated. With these accurate identifications of specific HAdV types and an epidemiological database of regional HAdV pathogens, along with the HAdV genome stability noted across time and space, the development, availability, and deployment of appropriate vaccines are needed.

Meshless methods have attracted great attention due to their advantage in geometric representation. In this paper, a meshless element-free Galerkin method is applied for the first time to solve pulsed eddy-current problems. Detailed mathematical derivations and the numerical implementation are discussed. The model is validated against analytic solutions for two canonical cases.

In nondestructive testing, uncertainties due to variabilities in inspection parameters can affect the accept/reject decision of a flaw. The concept of probability of detection (POD) offers a measure for quantifying the capabilities of nondestructive evaluation (NDE) systems in the presence of various sources of uncertainty. This paper presents a model based POD evaluation technique for magnetic flux leakage (MFL) inspection of natural gas transmission pipelines. The technique consists of two parts: finite element (FE) prediction and a parametric functional model. The procedures and results of evaluating PODs with respective to experimental parameters such as sensor liftoff, magnetization level, and sensor spacing are described in this paper.

Compared with the conventional finite element method that relies on an underlying mesh and element-node connectivity to describe the geometry, meshless method shows its advantage in mesh simplification, tight crack representation and re-meshing process. An effective numerical implementation of the meshless method uses the Galerkin technique and is referred to as the element-free Galerkin (EFG) method. In this paper, the EFG method is applied to a field of electromagnetic computation, namely, simulation of pulsed eddy current testing. The model is validated against analytical solutions.

Conventional finite-element methods (FEMs) rely on an underlying tessellation to describe the geometry and the basis functions that are used to represent the unknown quantity. Alternatively, however, it is possible to represent both the geometry and basis as a set of points. This alternative scheme has been used extensively in solid mechanics to compute stress and strain distributions. This paper presents an adaptation of the scheme to the analysis of electromagnetic problems in both the static and quasi-static regimes. It validates the proposed model against both analytical solutions and benchmarked FEMs. The paper demonstrates the efficacy of the proposed method by applying it to a range of problems.